The present invention relates to a method for producing a layer-like composition of oxide-ceramic superconductive material with a high transition temperature and large current-carrying capacity on the basis of a system of materials containing metallic components and oxygen with which method the metallic components of the system are applied in a physical deposition process while oxyqen is being supplied to a predetermined substrate as a preliminary product with a structure still disordered with respect of the metal oxide phase to be developed, which structure is converted into the desired superconducting metal oxide phase, using a heat treatment and while continuing the oxygen supply. Such a method is known, for instance, from "Physical Review Letters", Vol. 58, No. 25, June 22, 1987, pages 2684 to 2686.
Films or thin layers of superconducting metal oxide compounds such as on the basis of a material system Me1-Me2-Cu-0 (Me1=rare earths including yttrium; Me2=earth alkali metals) with high transition temperatures T.sub.c of, for instance, 40 K or about 90 K are often produced with special vapor deposition or sputtering processes. Here, a preliminary product of the components of the chosen material system with its structure is deposited which still has fault structures with respect to the super-conducting metal oxide phase on a suitable substrate This preliminary product is subsequently converted into material with a desired super-conducting phase generally by an annealing treatment which must generally be carried out while oxygen is being supplied.
The superconducting metal oxide phases which can be obtained in this manner and the structures of which may be similar to that of a perowskite, have, in the case of (La-Me2).sub.2 CuO.sub.4-y (with y.gtoreq.0), a tetragonal K.sub.2 NiF.sub.4 structure (see "Japanese Journal of Applied Physics", Vol. 26, No. 2, Part II-Letters, February 1987, pages L123 and L124). In contrast thereto, an orthorhombic structure is assumed in the case of YBa.sub.2 Cu.sub.3 O.sub.7-x (see, for instance, "Europhysics Letters", Vol. 3, No. 12, June 15, 1987, pages 1301 to 1307). Since these materials exhibiting these superconducting phases resemble an oxide ceramic, the corresponding high-T.sub.c superconductors are also called oxide-ceramic superconductors.
In addition, it is also known from the publication "Phys. Rev. Lett.", mentioned above to produce monocrystalline films of the system YBa.sub.2 Cu.sub.3 O.sub.7-x (x.apprxeq.0) on a monocrystalline SrTiO.sub.3 substrate. To this end, the three metallic components of the system are first vapor deposited from separate evaporation sources in an oxygen atmosphere to the substrate heated to about 400.degree. C. The preliminary product so obtained however still has a (disordered) structure. By means of a subsequent treatment at a high temperature of about 900.degree. C., while oxygen is being supplied, epitaxially grown single crystals of the desired super-conducting high-T.sub.c phase are then obtained. The films so prepared exhibit a high current-carrying capacity of more than 10.sup.5 A/cm.sup.2 at 77 K.
The current densities of 10.sup.5 A/cm.sup.2 achieved with the epitaxial Y-Ba-Cu-0 films at 77 K seem to make the use of these films as a wiring plane in integrated circuits with, for instance, HEM transistors (High Electron Mobility transistors) possible as active elements. The use of the substrate of SrTiO.sub.3 described in the publication "Phys. Rev. Lett." requires, however, to start in the assembly of such an integrated hybrid circuit with the, of necessity, sole wiring plane of the super-conductive material mentioned. The circuit of a semiconducting material would then have to be built-up on this plane. Similar techniques are under control so far only for Si semiconductor circuits. In addition, they are connected with a loss of quality and can be carried out only at great expense of equipment and therefore, financial means.